1. Field of the Invention
This invention relates to a combination brake valve module for use in a tractor-trailer combination, including semi-trailer configurations. Specifically, this invention discloses a multi-functional, compact, integrated brake valve module for use in fluid pressure brake systems incorporating a proportioning apparatus for modulating the braking effort to the tractor single or tandem rear service brake circuits, a tractor fluid pressure protection system in the event of trailer separation from the tractor, quick-release pressure orifices for venting residual fluid pressure from the combination brake valve module and trailer service brake circuit, integrated check valves for insuring fluid pressure integrity through the combination brake valve module, and stop lamp switching control for activation of the tractor-trailer combination rear stop lamp units. The module may optionally be provided with fluid pressure relay valves for control of the tractor or tractor-trailer combination service brake circuits.
2. Description of the Prior Art
In the past, brake systems for tractor-trailer combinations, such as semi-trailer configurations, have adopted braking systems that utilize a pressurized fluid for control of the service and parking brakes. The pressurized fluid, generated by a compressor provided on the tractor unit and typically driven by the vehicle engine, is usually ported to two independent pressurized fluid reservoirs. Through a series of actuation valves, a pressure signal is provided to various relay valves arranged in the brake pressurized fluid system to port the pressurized fluid from the fluid reservoirs to the appropriate brake application device, such as a diaphragm-type service brake cylinder.
Recently, an addition to the service brake circuit has been a proportioning apparatus for modulating the braking effort to the tractor single or tandem rear service brake circuits. Further, an integrated and independent pressurized fluid circuit is provided to deliver pressurized fluid from the fluid reservoirs to hold-off spring-type parking brake actuators allowing vehicle movement. Thus, to achieve the proper performance of the aforementioned generalized braking system, the prior art systems required a multiplicity of non-integrated components which were characterized by complexity, substantial space requirements, higher component costs, greater installation and maintenance charges and associated problems.
The multi-functional, compact, integrated brake valve module of the present invention lends itself to the same function of braking systems as employed in the prior art and accomplishes substantially the same functions with enhanced performance. As will be apparent from the description herein, the brake valve module of the present invention also results in less complexity, fewer components and attendant packaging simplification. Further, the brake valve module of the present invention replaces original equipment manufactured (OEM) tractor protection valves in existing vehicles to add additional features and functions (i.e., proportioning apparatus for modulating the braking effort to the tractor single or tandem rear service brake circuits) that could not heretofore be economically and advantageously introduced into the brake pressurized fluid circuit. This simplification provides the potential for enhanced reliability, reduced investment, and lower installation and maintenance costs.
In general, the functions which the combination brake valve module of the present invention carries out include the following:
(a) It provides proportioning apparatus for modulating the braking effort to the tractor single or tandem rear service brake circuits.
(b) It provides tractor fluid pressure protection in the event of trailer separation from the tractor.
(c) It provides quick-release pressure orifices for venting residual fluid pressure in the combination brake valve module and trailer service brake circuit.
(d) It provides integrated check valves for insuring fluid pressure integrity through the combination brake valve module.
(e) It provides convenient stop lamp switching control for activation of the tractor-trailer combination rear stop lamp units.
Additionally, as an optional configuration, the combination brake valve module of the present invention can be arranged to provide fluid pressure relay valves for control of the tractor or tractor-trailer combination service brake circuits.
Accordingly, it is an objective of this invention to provide an integrated, pressurized fluid control module performing a multiplicity of functions for control of the service and parking brake circuits of a tractor rear brakes and trailer brakes.
It is a further object of this invention to provide a pressurized fluid control module which incorporates a rear tractor service brake proportioning apparatus, a tractor protection system, a quick release pressure orifice, integrated check valves and a stop lamp switch.
It is an additional objective of this invention to provide an integrated pressurized fluid control module that is small, compact, easily packaged and more reliable than currently used system components.
It is still another object of this invention to provide additional capability of the pressurized fluid control module by adding the rear tractor service brake relay valve to the integrated unit.